The rapid and accurate identification of bioagents is a vital task for first-responders in order to facilitate timely and appropriate actions in the event of a biological attack. Bacillus anthracis, a spore-forming bacterium and a dangerous pathogen for the disease anthrax, is an important example. B. anthracis bacteria exist in two different forms: rod-shaped organisms and spores. Rod-shaped organisms grow and divide in a nutrient rich environment. When the food supply is depleted, the organisms turn into spores that can survive for decades. Structurally, a spore consists of a central core cell surrounded by various protective layers. Calcium dipicolinate (CaDPA) exists in these protective layers and accounts for ˜10% of the spore's dry weight (Bailey et al., 1965, J. Bacteriol. 89:984-987) therefore, it is a useful biomarker for bacillus spores (Goodacre et al., 2000, Anal. Chem. 72:119-127).
Among the potential biological warfare agent candidates, B. anthracis spores are of particular concern. First, they are highly resistant to environmental stress and are relatively easily produced into weapon-grade material outside the laboratory. Second, anthrax is an infectious disease, requiring medical attention within 24-48 h of initial inhalation of more than 104 B. anthracis spores (Walt and Franz, 2000, Anal. Chem. 72:738 A-746A). However, the diagnosis of anthrax is not immediate because it takes 1-60 days for anthrax symptoms to appear in humans (Chin, 2000, Control of Communicable Diseases Manual; American Public Health Association: Washington, D.C., pp 20-25). Therefore, the rapid detection of B. anthracis spores in the environment prior to infection is an extremely important goal for human safety.
Thus, a great need exists for a rapid and sensitive detection protocol suitable for use by first responders to detect dangerous microorganisms (e.g., anthrax) that may be used in a biological attack. Furthermore, such materials and methods should be portable for use in the field at potential sites of exposure and capable of providing results on site in short order.